Method and apparatus for decompressing a compressor

ABSTRACT

Methods, computer readable media, and apparatus are disclosed for decompressing an air compressor. The methods including compressing air, the compressed air flowing through a first path through a first non-return valve to a first receiver; and in response to determining to take the air compressor off-load, closing an air inlet valve of the air compressor to stop air from entering the air compressor, opening a second path from the air outlet of the air compressor to approximately atmospheric pressure to lower the air pressure at the air inlet of the air compressor, stopping a first flow of oil from the first receiver to the air compressor, wherein the first flow of oil is for cooling the compressor, stopping a second flow of oil from a separator for a working air to the air compressor, and flowing oil from the first receiver to the air compressor for lubrication.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Ser. No. 61/704,022 filed Sep. 21, 2012, the contents of which are incorporated herein by reference in their entirety.

BACKGROUND

In the discussion of the background that follows, reference is made to certain structures and/or methods. However, the following references should not be construed as an admission that these structures and/or methods constitute prior art. Applicant expressly reserves the right to demonstrate that such structures and/or methods do not qualify as prior art.

Air compressors deliver a source of compressed air that may perform many useful functions. One example of where air compressors are used is for drilling rigs. Although the explanation that follows is limited to drilling rigs, it should be understood that the disclosed air compressor system and methods of operation thereof are not limited to drilling rigs. Some drilling rigs operate as follows. A drill bit of a drill string (which is one or more drill pipes connected together) is rotated to drill a hole in the ground, i.e., in earth and/or rock. In order to flush the cuttings from the hole as it is being drilled, an air compressor may be used to deliver pressurized air which is communicated downwardly through the drill string to the front face of the drill bit. The cuttings get caught in the airflow from the drill bit and are brought to the surface as the air travels upwardly along the exterior of the drill string. The pressurized air may also serve to cool the cutting elements of the drill bit. This is one way compressed air may be used by drilling rigs.

Compressed air may also be used in percussive drilling where the compressed air is used to reciprocate an impact piston which applies percussive blows from a piston to a rotating drill bit to enhance the cutting action. The piston may be disposed below the ground surface immediately above the drill bit (i.e., a so-called down-the-hole hammer), or it may be disposed above the surface of the drill hole.

In many compressed air applications it is common to drive the air compressor by a engine (for example a fuel-driven engine or an electrically driven motor), which may also drive other equipment, such as a hydraulic system which may function to perform the following functions: power hydraulic systems to raise and lower the drill string, rotate the drill string via a gearbox, add drill rods to the drill string as drilling progresses, remove drill rods from the drill string as the drill string is being withdrawn from the hole, raise and lower a drilling mast, raise and lower leveling jacks, and propel the drilling rig (in the case of a mobile drilling rig). The engine also may drive a hydraulic pump and a cooling fan of a cooling system.

The compressed air needs of such a drilling machine are associated with the supplying of flushing air for flushing cuttings and/or driving the impact piston of a percussive tool and/or other accessories that may be used by the drilling rig. During operation of the drilling rig, there may be no need for pressurized air, such as during the adding or removal of drill rods, relocating the drill rig, setting up the drill rig, lunch breaks. Although there is no need during those periods to circulate compressed air to flush cuttings or to reciprocate the impact piston, it still may be necessary to drive the engine (that drives both the air compressor and the hydraulics) in order to continue to power the hydraulics.

In some air compressing systems, the drive connection between the air compressor and the engine is such that the air compressor is driven whenever the engine is driven, despite the fact that continuous operation of the air compressor is not necessary when drilling is not taking place.

There are certain measures that could be taken to further reduce the unnecessary consumption of energy. For example, a clutch could be provided between the engine and the air compressor to unload the compressor during periods of low air requirements, but that would add considerable cost to the equipment, and the clutch would rapidly wear in situations where the compressor has to be unloaded frequently. Additionally, it is uneconomical and impractical to switch the compressor on and off at frequent intervals. Moreover, even during periods where a large quantity of compressed air is not needed, smaller quantities may still be needed, so that the air compressor may have to cycle on and off to keep an air reservoir (a place where pressurized air from the air compressor may be stored) sufficiently pressurized for the smaller quantities.

Another possible energy-saving measure involves the provision of a variable speed gear drive for unloading the air compressor, but such a drive is complicated and relatively expensive, as would be a two-speed gear drive with clutches. With a variable speed gear drive, the revolutions per minute (RPMs) from the motor that are driving the air compressor could be reduced for reduced energy consumption.

Another possible measure involves driving the air compressor with a hydraulic motor that can easily be stopped or slowed during periods of low pressure requirements. For example, when a drill rod is being added to the drill string. However, such drives are relatively inefficient (many are at most 80% efficient), so any energy savings realized during periods of low compressed air consumption would likely be lost during periods of high air compressed consumption.

Therefore, it would be desirable to provide an air compressing system employing an engine-driven air compressor which is energy efficient.

SUMMARY

Methods, computer readable media, and apparatuses for decompressing an air compressor are disclosed that take an air compressor offline in an efficient manner so as not to put strain on the driving engine.

An air compressor system is disclosed. The air compressor system may include an air compressor having an air inlet and an air outlet, the air compressor configured to compress air from the air inlet and to deliver a volume of compressed air to the air outlet; an adjustable air inlet valve connected to the air inlet of the air compressor, wherein the adjustable air inlet valve is configured to be adjustable to regulate how much air can flow into the air inlet of the air compressor; a first receiver having an air inlet and an air outlet, the first receiver configured to store compressed air; a main air discharge passage connected to the air outlet of the air compressor and the air inlet of the first receiver; a first non-return valve disposed in the main air discharge passage between the air outlet of the air compressor and the air inlet of the receiver;

The air compressor system may include a second receiver having an air inlet and an air outlet, the second receiver configured to store compressed air; a secondary discharge passage connected to the air inlet of the second receiver and the main air discharge passage upstream from the first non-return valve; an oil separator disposed in the first receiver; a first oil line disposed to permit oil to flow from the oil separator to the air compressor; a first oil stop valve disposed in the first oil line and configured to have an open position where oil can flow between the oil separator and the air inlet of the air compressor and a closed position where the oil cannot flow between the oil separator and the air inlet of the air compressor; a second oil line disposed to permit oil to flow from the first receiver to the air compressor; a second oil stop valve disposed in the second oil line and configured to have an open position where oil can flow from the first receiver to the air compressor and a closed position where oil cannot flow from the first receiver to the air compressor; an isolation valve disposed in the air flow between the main air discharge passage and the air inlet of the second receiver, wherein the isolation valve is configured to have an open position where air from the main air discharge passage can flow through the secondary discharge passage and a closed position where air from the main air discharge passage cannot flow through the secondary discharge passage; and a controller in communication with the adjustable air inlet valve and isolation valve, wherein the controller is configured to take the air compressor off load by shutting the adjustable air inlet valve and opening the isolation valve, wherein the first oil stop valve and the second oil stop valve are configured to be open when the air compressor is on load and to be closed when the air compressor is off load.

The air compressor system may include a second non-return valve disposed in the air flow between the secondary discharge passage and the air outlet of the second receiver.

The air compressor system may include a third oil line configured to permit oil to flow from the first receiver to the air compressor.

The controller may be further configured to first shut the adjustable inlet valve and then after waiting a predetermined time to open the isolation valve.

The second non-return valve may be configured to maintain the second receiver at approximately atmospheric pressure.

The air compressor system may include an engine configured to drive the air compressor.

An air pressure of the first receiver may be greater than an air pressure of the second receiver.

The second non-return valve may be disposed between the air outlet of the second receiver and atmospheric air.

The air compressor system may include a secondary air compressor having an air inlet and an air outlet, wherein the air inlet is disposed to compress air from the air outlet of the compressor to deliver a volume of compressed air to the air inlet of the second receiver, and wherein the controller is further configured to turn on the secondary air compressor after opening the isolation valve and closing the adjustable air inlet valve.

The air compressor may include a pressure sensor in communication with the controller and disposed to measure the pressure of the first receiver, wherein the controller is further configured to determine when to take the air compressor off load based at least partially on the measured air pressure of the first receiver, and wherein the controller is configured to take the air compressor off load by closing the adjustable air inlet valve, opening the isolation valve, and turning the secondary air compressor on.

The air compressor may include an oil line connected to the second receiver and connected to one of: the main discharge passage upstream from the first non-return valve, the main discharge passage downstream from the first non-return valve, and the first receiver.

The air compressor may include a second isolation valve in communication with the controller; a pressure sensor in communication with the controller and disposed to measure the pressure of the first receiver, wherein the controller is further configured to take the air compressor off load by determining a pressure of the first receiver, and if the if the pressure of the first receiver is below a threshold value then closing the isolation valve and opening the second isolation valve, otherwise opening the isolation valve and closing the second isolation valve; and a secondary air compressor having an air inlet and an air outlet, wherein the air inlet is disposed to compress air from the air outlet of the compressor to deliver a volume of compressed air to the secondary discharge passage, and wherein the controller is further configured to turn on the secondary air compressor after closing the adjustable air inlet valve.

The second oil stop valve may be an air pressure actuator in communication with an air pressure of the air outlet of the air compressor, and configured to be in the open position when the air pressure of the air outlet of the air compressor is above a threshold air pressure, and configured to be in the closed position when the air pressure at the air outlet of the air compressor is below a threshold air pressure.

A method of decompressing an air compressor having an air inlet and an air outlet is disclosed. The method including compressing air from an air inlet to an air outlet, the compressed air flowing through a first path through a first non-return valve to a first receiver; and in response to determining to take the air compressor off-load, closing an air inlet valve of the air compressor to stop air from entering the air compressor, opening a second path from the air outlet of the air compressor to approximately atmospheric pressure to lower the air pressure at the air outlet of the air compressor, stopping a first flow of oil from the first receiver to the air compressor, wherein the first flow of oil is for cooling the compressor, stopping a second flow of oil from a separator for a working air to the air compressor, and flowing oil from the first receiver to the air compressor for lubrication.

The opening a second path may include opening a second path by opening a second non-return valve from the air outlet of the air compressor to a second receiver, wherein the second receiver is at approximately atmospheric pressure.

Opening a second path may include opening a second path by opening an isolation valve, wherein the isolation valve is connected to the air outlet of the air compressor upstream from the first non-return valve.

Stopping air from entering the air inlet of the compressor may include stopping air from entering the air inlet of the air compressor by closing an air inlet valve of the compressor.

The method may include turning on a second air compressor disposed in the second path to suck air out of the air inlet of the air compressor.

The second reserve may be connected to a non-return valve and the non-return valve is connected to atmospheric pressure.

The method may include separating oil from the compressed air in the second receiver and flowing the oil to the first receiver.

A method of decompressing an air compressor having an air inlet and an air outlet is disclosed. The method may include compressing air from an air inlet to an air outlet, the compressed air flowing through a first path through a first non-return valve to a first receiver; and in response to determining to take the air compressor off-load, closing an air inlet valve of the air compressor to stop air from entering the air compressor, and if a receiver pressure is above a threshold, then opening a second path from the air outlet of the air compressor to approximately atmospheric pressure, otherwise opening a third path from the air outlet of the air compressor to the first receiver.

The method may include stopping a first flow of oil from the first receiver to the air compressor, wherein the first flow of oil is for cooling the compressor, stopping a second flow of oil from a separator for a working air to the air compressor, and flowing oil from the first receiver to the air compressor for lubrication.

A computer readable non-transitory medium including instructions which when executed in a processing system cause the processing system to execute a method for decompressing an air compressor is disclosed. The method may include compressing air from an air inlet to an air outlet, the compressed air flowing through a first path through a first non-return valve to a first receiver; and in response to determining to take the air compressor off-load, closing an air inlet valve of the air compressor to stop air from entering the air compressor, opening a second path from the air outlet of the air compressor to approximately atmospheric pressure to lower the air pressure at the air inlet of the air compressor, stopping a first flow of oil from the first receiver to the air compressor, wherein the first flow of oil is for cooling the compressor, stopping a second flow of oil from a separator for a working air to the air compressor, and flowing oil from the first receiver to the air compressor for lubrication.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding may be had from the following description, given by way of example in conjunction with the accompanying drawings wherein:

FIGS. 1A, 1B, 1C schematically illustrate an example of an air compressor system for taking the air compressor from on load to off load;

FIG. 2 schematically illustrates the air compressor system in an off load state with an evacuation pump;

FIGS. 3A, 3B, and 3C schematically illustrates an alternative embodiment of the air compressor system in an off load state with a second isolation valve that provides a parallel configuration and a serial configuration;

FIG. 4 schematically illustrates an example of a method for taking an air compressor on load and off load;

FIG. 5 schematically illustrates an application of the working air;

FIG. 6 schematically illustrates an embodiment of the air compressor system that includes a three way valve, a scavenger line, and a third oil stop valve; and

FIG. 7 illustrates an example graph illustrating the operation of an example of the invention when the air compressor is off load.

DETAILED DESCRIPTION

FIGS. 1A, 1B, 1C schematically illustrate an example of an air compressor system 100 for taking the air compressor 20 from an on load state to an off load state.

FIG. 1A schematically illustrates an air compressor system 100 in an on load state delivering working air 44 where adjustable air inlet 12A is in an open position and isolation valve 12B is in a closed position. The air compressor 20 is in an on load state when it is compressing air and in an off load state when it is not compressing a substantial amount of air. The air compressor system 100 for taking the air compressor 20 off load provides for reducing the air pressure within the air compressor 20 so that the motor 18 does not have to work as hard to turn the air compressor 20 when the air compressor system 100 does not need to deliver working air 44. The air compressor system 100 is taken from an on load state (FIG. 1A) to an off load state (FIGS. 1B and 1C). FIG. 1B is an optional state where the adjustable air inlet 12A is closed and the isolation valve 12B is closed. In FIG. 1C, the isolation valve 12B goes from a closed state as illustrated in FIGS. 1A and 1B to an open state.

Referring to FIG. 1A, the air compressor system 100 takes air in through an air filter 10 and compresses the air with an air compressor 20 and delivers the compressed air as working air 44, which could be used for many applications including drilling.

The embodiment of the air compressor system 100 illustrated in FIG. 1 includes an air filter 10, an adjustable inlet valve 12A, a solenoid 14A (to control the adjustable inlet valve 12), an engine 18, an air compressor 20, an air inlet of the air compressor 19, an air outlet of the air compressor 21, a controller 22, communication lines 88A, 88B, 88C, 88D a primary discharge passage 50, a first non-return valve 80, a first receiver 34, an air inlet of the first receiver 74, an air outlet of the first receiver 35, an oil separator 37, optionally, a working air outlet valve 36, a secondary discharge passage 82, an isolation valve 12B, a solenoid 14C (to control the isolation valve), an oil separator 70 or second receiver 70, an air inlet of the oil separator 90, an air outlet of the oil separator 92, optionally, a second non-return valve 72, and optionally, a muffler 78. As illustrated, the oil lines 39 are dotted, and some of the optional components 72, 78, 60, 62, 14D, 36 are more lightly dotted. The air passages 19, 21, 50, 74, 35, 82, 90, 92 are not dotted. Some optional components 10 are not dotted. Optional components are indicated as such in the text, and as such there should be no implication that because a component or an embodiment of a component is not dotted that it is necessary for a particular embodiment.

Additionally, the air compressor system 100 includes an oil system to provide oil to the air compressor 20. The oil system provides oil for lubricating the air compressor 20 and may cool the air compressor 20. The oil system includes a first oil line 39A, an oil stop valve 24A, an air pressure actuator 46, a second oil line 39B, a third oil line 39C, an oil stop valve 24B, a solenoid 14B to control the oil stop valve 24B, a fourth oil line 39D, optionally, an oil evacuation pump 60, optionally, an evacuation motor 62, optionally, a third non-return valve 73, and a solenoid 14D to control the evacuation motor 62, which may be in communication with the controller 22. Also illustrated in FIG. 1A is working air 44.

The air filter 78 may be a filter to filter air. The adjustable inlet valve 12A may be an inlet butterfly valve. The adjustable inlet valve 12 may be biased by a spring to be in a default state of closed. The solenoid 14A may be disposed to adjust the adjustable inlet valve 12 to open an adjustable amount to change an amount of air that can flow to the air inlet 19 of the air compressor 20. The solenoid 14A (to control the adjustable inlet valve 12) may be an electrical device that produces a magnetic field when current is applied. The adjustable inlet valve may also be operated by an electrical, hydraulic, or pneumatic actuator in communication with the controller 22. The solenoid 14A may be in electrical communication with the controller 22 via control line 88A.

The engine 18 may be an electric engine or a gasoline motor or a hydraulic motor. The engine 18 may be used for other operations other than driving the air compressor 20. In embodiments, the engine 18 does not in normal operation disengage from the air compressor 20. The air compressor 20 may be a screw air compressor or another type of air compressor 20. The air inlet 19 of the air compressor 20 may be an air inlet 19 of the air compressor 20. The air outlet 21 of the air compressor 20 may be an air outlet 21 of the air compressor 20.

The controller 22 may be a programmable logic controller (PLC). The controller 22 may be in electrical communication with the solenoids 14A, 14B, 14C, and 14D. The controller 22 may be configured to control the operation of the air compressor system 100.

The primary discharge passage 50 may be an air pipe constructed out a suitable material for conveying compressed air and oil. The non-return valve 80 may be a valve which allows air and oil to flow through it in only one direction from the air compressor 20 to the receiver 34. The receiver 34 may be an air receiver constructed of suitable material for storing compressed air and for filtering oil from the compressed air. The air inlet of the receiver 74 may be an air inlet of the receiver 34. The air outlet of the receiver 35 may be an air outlet of the receiver 35. The oil separator 37 may be an oil separator configured to separate oil from the compressed air prior to the compressed air flowing through the air outlet 35 of the receiver 34.

A working air outlet valve 36 may be an air valve operable by a user of the air compressor system 100. The working air outlet valve 36 may communicate the compressed air from the air outlet of the receiver 35 with an application that uses the working air 44, which as illustrated in FIG. 1A is being vented to the atmospheric air.

The secondary discharge passage 82 may be a pipe constructed out of a suitable material for conveying compressed air and oil. The isolation valve 12B may be an electrically controlled valve having two positions: a spring biased closed position as the default position and an open position that is switched to when current is applied to the solenoid 14C. The open position (FIG. 1C) may allow air and oil to flow through it from the air compressor 20 to the oil separator 70. The solenoid 14C (to control the isolation valve 12B) may be an electrical device that produces a magnetic field when current is applied. The solenoid 14C may be in electrical communication with the controller 22 via communication line 88B.

The oil separator 70 may be an air receiver constructed of suitable material for storing compressed air. The oil separator 70 may be constructed of suitable material for separating the oil and air so that the oil can be returned to the air compressor 20. In embodiments, the oil separator 70 is a receiver. In embodiments, the oil separator 70 may include be a receiver with an oil separator. The optional second non-return valve 72 may be a valve which allows air to flow through it in only one direction from the oil separator 70 to the optional muffler 78. The optional muffler 78 may be shaped to muffle sound from the escape of compressed air from the second non-return valve 72.

The first oil line 39A may be a line suitable for transporting oil from the receiver 34 to the air compressor 20. Oil stop valve 24A may be an oil stop valve 24A configured to control the flow of oil from the receiver 34 to the air compressor 20 in the first oil line 39A. The oil stop valve 24A may be a controlled valve having two positions: a closed position as a default and an open position that the oil stop valve 24A switches to when pressure is applied to the pressure actuator 46. The oil stop valve 24A may have a spring that keeps the oil stop valve 24A in the closed position unless the air pressure actuator 46 pushes on the oil stop valve 24A. The air pressure actuator 46 may be an actuator in communication with the air pressure of the air outlet 21 of the compressor 20 and the oil stop valve 24A via air line 51. When the air pressure of the air compressor 20 rises past a threshold shutoff oil air pressure the air pressure actuator 46 opens the oil stop valve 24A and when the air pressure of the air compressor 20 falls below a predetermined shutoff oil air pressure the air pressure actuator 46 no longer opens the oil stop valve 24A, so the oil stop valve 24A closes.

The second oil line 39B may be an oil line 39B suitable for transporting oil from the receiver 34 to the air compressor 20. Third oil line 39C may be an oil line 39C suitable for transporting oil from the oil separator 37 to the air inlet 19 of the air compressor 20. The oil separator 37 may separate oil from the compressed air prior to the compressed air flowing out the air outlet 35 of the receiver 34. The oil stop valve 24B may be configured to stop the flow of oil from the oil separator 37 to the air compressor 20. The transceiver 14B may be configured to control the oil stop valve 24B and may be in communication with the controller 22. The third oil line 39 may transport oil from the oil separator 37 to a place other than the air inlet 19 of the air compressor 20 so that the oil reaches the air compressor 20.

The fourth oil line 39D may be a line suitable for transporting oil from the oil separator 70 to the receiver 34. The fourth oil line 39D may transport the oil from the oil separator 70 to a different place in the air compressor system 100 such as to the air inlet 19 of the air compressor 20. The evacuation pump 60 may be a pump suitable for pumping oil from the oil separator 70 to the receiver 34. The evacuation motor 62 may be a motor suitable for driving the evacuation pump 60. The solenoid 14D controls the operation of the motor 62 and may be in communication with the controller 22.

In operation, the controller 22 controls the operation of the air compressor system 100. The following is a description of the air compressor system 100 delivering working air 44 when the adjustable air inlet valve 12A is at least partially open, the isolation valve 76 is closed, and the working air outlet valve 36 is open. Air flows through the air filter 10 and is filtered by the air filter 10. The air flows through the adjustable air inlet valve 12A, which is configured to control the amount of air that can flow through the adjustable air inlet valve 12A. The controller 22 controls how open the adjustable air inlet valve 12A is by providing electricity to the solenoid 14A. By adjusting the adjustable air inlet valve 12A the controller 22 can control the volume of compressed air delivered by the air compressor 20. This may be called throttling the air compressor system 100 by controlling the opening of the adjustable air inlet valve 12A. As discussed above it may be impractical to control the volume of compressed air delivered by the air compressor 20 by controlling the engine 18 that drives the air compressor 20 or by controlling the connection between the air compressor 20 and the engine 18 (for example, gears or clutch.)

The air that flows through the adjustable air inlet valve 12A flows into the air inlet 19 of the air compressor 20 and is compressed by the air compressor 20, which delivers a volume of compressed air to the air outlet 21 of the air compressor 20. The air compressor 20 is driven by the engine 18. The controller 22 may receive an indication how fast the motor 18 is going, but, in embodiments, the controller 22 cannot change the speed of the engine 18 (this may be because the air compressor system 100 may be only one application that is being driven by the engine as discussed above.) In embodiments, the controller 22 may be able to change the speed of the engine 18.

The compressed air 20 then flows through the main air discharge passage 50 and through the non-return valve 80. The non-return valve 80 permits oil and air to flow through it in only the direction from the air outlet of the compressor 21 toward the air inlet 74 of the receiver 34. Because the non-return valve 80 permits oil and air to flow only in one direction, the pressure may be different on the air compressor 20 side of the non-return valve 80 than the air pressure on the receiver 34 side of the non-return valve 80.

The compressed air then flows into the air inlet 74 of the receiver 34. The receiver 34 may provide two functions for the air compressor system 100. First, it may provide for oil recirculation, which will be discussed below. Second, it may provide a means of storing compressed air so that the air compressor 20 does not have to deliver compressed air all the time when only relatively small amounts of compressed air are required for accessory use through the accessory compressed air supply line (not illustrated) or when only relatively small amounts of compressed air are required for oil recirculation to maintain oil to the air compressor 20.

The compressed air then flows out of the air outlet of the receiver 35 and through the working air outlet valve 36. The working air outlet valve 36 may be operable by a user of the air compressor system 100 to operate either in an open or closed state. In alternative embodiments, the working air outlet valve 36 may be controlled by the controller 22. After flowing through the working air outlet valve 36, the compressed air then flows out into the atmospheric air as illustrated. Many applications are possible for the working air 44 including flushing air for drilling applications.

Thus, the air compressor system 100 is configured to deliver working air 44. The air compressor system 100 may be said to be on load since it is compressing air from the air inlet 19 to the air outlet 21, which in this case is being delivered as the working air 44. The compressed air may be delivered to the receiver 34 when the working air outlet valve 36 is closed. The adjustable air inlet valve 12A may be called an output control of the air compressor system 100 because it controls the volume of air produced by the air compressor system 100.

The following describes the operation of the oil system of the air compressor system 100 when the air compressor 20 is on load as illustrated in FIG. 1A. The oil system may be used to lubricate and cool the air compressor 20. When the air compressor 20 is on load, the following is a path the oil may follow to lubricate the air compressor 20. The oil may be used to lubricate the air compressor 20. The oil may then flow from the air compressor 20 through the main air discharge passage 50 through the non-return valve 80, and into the receiver 34. In embodiments, the receiver 34 maintains a minimum pressure for conveying the oil back to the air compressor 20. The oil may then flow from the receiver 34 through a first oil line 39A and through an oil stop valve 24A and through to the air compressor 20. Since the air compressor 20 is on load the pressure is large enough for the air pressure actuator 46 to open the oil stop valve 24A, so oil can be conveyed from the receiver 34 through the oil stop valve 24A to the air compressor 20. The oil may be cooled and/or filtered prior to returning to the air compressor 20. The cooling and filtering are not illustrated. The pressure necessary to keep the oil stop valve 24A open may be a threshold oil opening pressure. Additionally, oil flows through a second oil line 39B from the receiver to the air compressor 20. In embodiments, the first oil line 39A and the second oil line 39B together provide a volume of oil sufficient to lubricate and cool the air compressor 20 when the air compressor 20 is on load. In embodiments, the first oil line 39A and the second oil line 39B may be combined into a single oil line where the amount of oil that flows through the single line is controlled based on whether or not the air compressor 20 is on or off load.

The oil separator 37 separates oil from the compressed air prior to the compressed air flowing out of the air outlet 35 of the receiver 34. Without the oil separator 37 the working air 44 would include oil that may be unsuitable for the application the working air 44 is being used for. Additionally, without the oil separator 37, oil included in the working air 44 would have to be replaced to maintain oil levels in the air compressor system 100. The oil may then flow through the fourth oil line 39C. The oil stop valve 24B is generally open when the air compressor 20 is online. In embodiments, when the air compressor 20 is on load significant amounts of oil are not flowing through the fourth oil line 39D.

FIG. 1B schematically illustrates the air compressor system in an off load state where the adjustable air inlet 12A is in a closed position and the isolation valve 76 is in a closed position. The adjustable air inlet valve 12 is closed so the air compressor 20 is in an off load state because it is not compressing a significant amount of air due to air not being available. However, as discussed above, the air compressor 20 may still be driven by the motor 18 because it may not be practical to adjust the motor speed to control the amount of air that is compressed by the air compressor 20.

In operation, the system to take the air compressor 20 on and off load works as follows. The controller 22 determines that the air compressor system 100 does not need the air compressor 20 to generate additional compressed air. The controller 22 then closes the adjustable inlet valve 12A (FIGS. 1B and 1C), and opens the isolation valve 12B (FIG. 1C), and, may if there is an evacuation pump 86 (FIG. 2) turn the evacuation pump 86 on. In embodiments, the optional evacuation pump 86 may already be on. Since the adjustable inlet valve 12A is closed, the air compressor 20 no longer has a source of air to compress. The air compressor system 100 may go from the state illustrated in FIG. 1A to the state illustrated in FIG. 1B where the adjustable air inlet 12A is closed, and then from the state illustrated in FIG. 1B to the state illustrated in FIG. 1C where the isolation valve 12B is opened and, optionally, the evacuation compressor 86 is turned on. In embodiments, the air compressor system 100 may go directly from the state illustrated in FIG. 1A to the state illustrated in FIG. 1C. When the controller 22 determines that the air compressor 20 needs to go from the off load state to the on load state, the air compress system 100 may close the isolation valve 12B to go from the state illustrated in FIG. 1C to the state illustrated in FIG. 1B, and then open the adjustable inlet valve 12A to go to the state illustrated in FIG. 1A. In embodiments, the air compressor system 100 may open the adjustable inlet valve 12A and close the isolation valve 12B nearly simultaneously to go directly from the state illustrated in FIG. 1C to the state illustrated in FIG. 1A.

When the adjustable air inlet 12A is first closed, there is some air between the adjustable air inlet 12A and the air compressor 20 that may be compressed and pushed to the air outlet 21 of the air compressor 20, and may be pushed through the non-return valve 80. The amount of air that is pushed through the non-return valve 80 depends, at least partially, on the pressure of the receiver 34 which, in the embodiment illustrated, resists the air being pushed through the non-return valve 80. The pressure in the receiver 34 may be large compared to the pressure in the oil separator or receiver 70. The advantage to closing the adjustable air inlet 12A and keeping the isolation valve 12B closed for a short period of time is that the air pressure at the air outlet 21 may be reduced. The air pressure at the air outlet 21 may be reduced to the air pressure of the receiver 34 plus the air pressure necessary to open the non-return valve 80. The air pressure at the air inlet 19 of the air compressor 20 is reduced because the air between the adjustable air inlet 12A and the air compressor 20 is compressed to the air outlet 21 of the air compressor 20.

FIG. 1B illustrates the first oil stop valve 24B and second oil stop valve 24A being off. In embodiments, the first oil stop valve 24B is turned off and the second oil stop valve is turned off when the air compressor 20 is off load. Oil stop valve 24A is configured to turn off in the off load state by a pressure of the air compressor 20. In other embodiments, the controller 22 may turn off oil stop valve 24A by, for example, a solenoid. The controller 22 may send an electrical signal to the oil isolation valve 24B to close the oil isolation valve 24B. The isolation valve 12B may also be operated by a hydraulic or pneumatic actuator in communication with the controller 22. The oil isolation valve 24B may be configured to close when the air compressor 20 is off load based on a pressure of the air compressor system 100. The oil isolation valve 24A may close based on an air pressure at the air compressor 20. Oil isolation valve 24A and oil isolation valve 24B may be turned off simultaneously or serially. Oil isolation valve 24A and oil isolation valve 24B may be configured to turn off, or be turned off by the controller 22, either prior to or after adjustable air inlet 12A valve is turned off. Oil isolation valve 24A and oil isolation valve 24B may be configured to turn off, or may be turned off by the controller 22 either prior to or after adjustable air inlet 12A valve is turned off.

Turning oil stop valve 24B off when the air compressor 20 is off load has the advantage of reducing the work needed to run the air compressor 20 because the oil recovered from the oil separator 37 does not go through the air compressor 20, and it may close off a passage for pressured air to travel between the receiver 34 and the air compressor 20. Turning oil stop valve 24A off when the air compressor 20 is off load has the advantage of reducing the work needed to run the air compressor 20 because the volume of oil that flows from the first receiver 34 to the air compressor 20 is reduced.

Although FIG. 1B illustrates the working air 44 being off, the compressed air in the air reserve 34 could be used as working air 44 or for other applications while the air compressor system 100 is off load. The air compressor 20 may come back on load if the pressure in the air reserve 34 falls below a threshold pressure.

FIG. 1C schematically illustrates the air compressor system 100 in an off load state where the adjustable air inlet 12A is in a closed position and the isolation valve 12B is in an open position, and oil stop valve 24B and oil stop valve 24A are off. In operation, the controller 22 may send an electrical signal to the solenoid 14C that changes the position of the isolation valve 12B from a closed position (FIGS. 1A and 1B) to an open position as illustrated in FIG. 1C.

Since adjustable inlet valve 12A is closed, the air compressor 20 is off load not compressing significant quantities of air. If the air pressure of the air remaining in the main discharge passage 50 is greater than the air pressure in the oil separator 70 plus, if the optional non-return valve 72 is present, the pressure necessary to open the non-return valve 72, then the air goes through the secondary discharge passage 82 and into the oil separator 70 and through the non-return valve 72 to atmospheric air. For example, if the atmosphere pressure is 1 atmosphere and it takes 0.1 atmosphere to open the non-return valve 72, then the pressure in the main discharge passage 50 and oil separator 70 will have to be 1.1 atmospheres to open the non-return valve 72 to vent some of the compressed air, and the air pressure in the discharge passage 50 and the oil separator 70 will be reduced to 1.1 atmospheres. The oil separator 70 separates the air from the oil so that the air may flow out of the non-return valve 72 and the oil may be re-circulated. The oil from the separator 70 may flow through oil line 39D to the first receiver 34. In operation, when air flows from the main discharge passage 50 to the oil separator 70, it may include oil which will accumulate at the bottom of the oil separator 70. In embodiments, the oil at the bottom of the oil separator 70 is pumped by evacuation pump 60 to the receiver 34. The evacuation pump 60 may include an evacuation motor 62 which may be controlled by the controller 22 via solenoid 14D. In embodiments, the evacuation motor 62 will operate based on oil pressure from the oil at the bottom of the oil separator 70. In embodiments, the oil at the bottom of the oil separator 70 is pumped to the main discharge passage 50.

The opening of the isolation valve 12B may reduce the air pressure at the air outlet 21 of the compressor 20 which may reduce the load of running the air compressor 20 for the motor 18. The fuel consumption of the motor 18 may be reduced due to the reduced load on the motor 18.

FIG. 2 schematically illustrates the air compressor system in an off load state with an evacuation pump 86 where the adjustable air inlet 12A is in a closed position and the isolation valve 12B is in an open position, and the first oil stop valve 24B and the second oil stop valve 24A are off. The air compressor system 100 may include an evacuation pump 86, solenoid 85, and control line 88E. In operation, the controller 22 sends an electrical signal to the solenoid 85 which causes the evacuation pump 86 to operate. The evacuation pump 86 sucks air from the air output 21 of the air compressor 20 and compresses the air and pushes the compressed air into the oil separator 70. If the optional non-return valve 72 is present, the compressed air flows out the non-return valve 72. And, if the optional muffler 78 is present, the air flows out through the optional muffler 78. The optional evacuation pump 86 may provide the advantage that the air pressure at the air outlet 21 of the air compressor 20 may be reduced further than the atmospheric air plus, if the optional non-return valve 72 is present, the pressure needed to open non-return valve 72. The reduced air pressure at the air outlet 21 of the air compressor 20 reduces the load needed for the motor 18 to drive the air compressor 20, which may reduce the fuel consumed by the motor 18. In embodiments, the evacuation pump 86 may push the compressed air into a receiver which includes an oil separator 70.

FIGS. 3A, 3B, and 3C schematically illustrates an alternative embodiment of the air compressor system in an off load state with a second isolation valve 12C that provides a parallel configuration and serial configuration. FIG. 3A illustrates the air compressor system 100 in a parallel configuration where isolation valve 12C is open and isolation valve 12B is closed. FIG. 3B illustrates the air compressor system 100 in a serial configuration where isolation valve 12C is closed and isolation valve 12B is open. FIG. 3C is an alternative embodiment of FIG. 3B where the evacuation pump 86 is disposed down stream of the isolation valve 12C. FIG. 3 includes an alternative air passage 87, isolation valve 12B, isolation valve 12C, non-return valve 85, and a pressure sensor 302.

The isolation valve 12C may be an isolation valve 12 configured to have an open position where air can flow from the secondary discharge passage 82 to the alternative air passage 87, and a closed position where air cannot flow from the secondary discharge passage 82 to the alternative air passage 87. The isolation valve 12C may include a solenoid 14E in communication with the controller 22 (via a control line not illustrated), which may be configured to open and close the isolation valve. The alternative air passage 87 may be an air passage line constructed out a suitable material for conveying compressed air and oil. The non-return valve 85 may be a valve that permits oil and air to flow through it only in the direction from the isolation valve 12C to the main air discharge passage 50. The pressure sensor 302 may be configured to determine a pressure of the first receiver 34. The pressure sensor 302 may be configured to communicate to the controller 22 the pressure of the receiver 34.

In FIG. 3A, the air compressor system 100 is off load with the secondary discharge passage 82 configured in a parallel configuration. The air compressor system 100 is in an off load state where the adjustable air inlet 12A is in a closed position, the first oil stop valve 24B is off, and the second oil stop valve 24A is off. The secondary discharge passage 82 is in a parallel configuration with isolation valve 12B closed and second isolation valve 12C opened. Evacuation pump 86 may be on. In operation, the air compressor 20 is off load as the adjustable air inlet valve 12A is closed. Motor 18 may still be operating the air compressor 20 as discussed above. In embodiments, the evacuation pump 86 sucks air from the air outlet 21 of the air compressor 20 where the air flows through the second isolation valve 12C and through the fourth non-return valve 85, and to the receiver 34. In embodiments, the controller 22 puts the air compressor system 100 into the parallel configuration when the pressure sensor 302 indicates that the pressure in the receiver 34 is relatively low. For example, the controller 22 may place the air compressor system 100 in the parallel configuration when the pressure in the receiver 34 is less than 150 PSI. Other valves for a threshold or predetermined value for the pressure of the receiver 34 may be used to determine when to use a parallel or serial configuration. For example, value may vary between 50 PSI to several thousand PSI.

In FIG. 3B, the air compressor system 100 is off load with the secondary discharge passage 82 configured in a serial configuration. The air compressor system 100 in an off load state where the adjustable air inlet 12A is in a closed position, the first oil stop valve 24B is off, and the second oil stop valve 24A is off. The secondary discharge passage 82 is in a serial configuration with isolation valve 12B open and second isolation valve 12C closed. Evacuation pump 86 may be on. In embodiments, evacuation pump 86 is not turned on in the serial configuration. In operation, the air compressor 20 is off load as the adjustable air inlet valve 12A is closed. The motor 18 may still be operating the air compressor 20 because, as discussed above, it may be difficult to disengage the motor 18 from the air compressor 20. In embodiments, the evacuation pump 86 sucks air from the air outlet 21 of the air compressor 20 and pushes the air through the isolation valve 12B and to the oil separator or receiver 70. In embodiments, the controller 22 puts the air compressor system 100 into the serial configuration when the pressure sensor 302 indicates that the pressure in the receiver 34 is relatively high. For example, the controller 22 may place the air compressor system 100 in the serial configuration when the pressure in the receiver 34 is greater than 150 PSI. In embodiments, one or more of the isolation valves 24 may be configured to switch to open and close based on the pressure of the receiver 34 without the controller 22 sending a signal to the isolation valve 24.

In FIG. 3C, the air compressor system 100 is off load with the secondary discharge passage 82 configured in a parallel configuration. FIG. 3C is an alternative embodiment of FIG. 3A where the evacuation pump 86 is down stream of the second isolation valve 12C. The air compressor system 100 is in an off load state where the adjustable air inlet 12A is in a closed position, the first oil stop valve 24B is off, and the second oil stop valve 24A is off. The secondary discharge passage 82 is in a parallel configuration with isolation valve 12B closed and second isolation valve 12C opened. Evacuation pump 86 may be on. In operation, the air compressor 20 is off load as the adjustable air inlet valve 12A is closed. Motor 18 may still be operating the air compressor 20 as discussed above. In embodiments, the evacuation pump 86 sucks air from the air outlet 21 of the air compressor 20 where the air flows through the second isolation valve 12C and through the fourth non-return valve 85, and to the receiver 34. In embodiments, the controller 22 puts the air compressor system 100 into the parallel configuration when the pressure sensor 302 indicates that the pressure in the receiver 34 is relatively low. For example, the controller 22 may place the air compressor system 100 in the parallel configuration when the pressure in the receiver 34 is less than 150 PSI. Other values for the pressure of the receiver 34 are possible, such as, for example, ranges from 50 PSI to thousands of PSI. In the embodiment illustrated in FIG. 3C the evacuation pump 86 can not be used in the serial configuration since the evacuation pump 86 is not in the flow of air in the serial configuration. The embodiment of FIG. 3C may have the advantage that the evacuation pump 86 may be large to provide the necessary pressure to push the air into the receiver 34, and it may not be efficient to turn on a large evacuation pump 86 in the serial configuration.

FIG. 4 schematically illustrates an example of a method 400 for taking an air compressor on load and off load. The method 400 begins with at start 402. The method 400 continues with compressing air from an air inlet to an air outlet, the compressed air flowing through a first path through a first non-return valve to a first receiver. For example, the air compressor system 100 of FIG. 1A is in an on load state. The air compressor 20 is compressing air from the air inlet 19 to the air outlet 21. The compressed air is pushed through the first non-return valve 80 to a first receiver 34.

The method 400 continues with take air compressor off load at 406. For example, the controller 22 of FIG. 1A may determine whether or not the air compressor system 100 needs to compress air. If the controller 22 determines that the air compressor 20 does not need to compress air, then the controller 22 may determine to take the air compressor 20 to an off load state. The method will return to 404 if the air compressor system determines not to take the air compressor to an off load state.

The method 400 continues with closing an air inlet valve of the air compressor to stop air from entering the air compressor at 408. For example, in FIG. 1B, the controller 22 has closed the adjustable air inlet valve 12A so that air may no longer flow into the air inlet 19 of the air compressor 20.

The method 400 continues with opening a second path from the air outlet to approximately atmospheric pressure to lower the air pressure at the air inlet of the air compressor at 410. For example, in FIG. 1C, the controller 22 opens the isolation valve 12B which permits air to flow from the air outlet 21 of the air compressor 20 to the oil separator 70. Steps 408 and 410 may be performed in the opposite order or may be performed simultaneously. Steps 408 and 410 may include stopping a first flow of oil from the first receiver to the air compressor, wherein the first flow of oil is for cooling the compressor, and stopping a second flow of oil from a separator to the air compressor, and flowing oil from the first receiver to the air compressor for lubrication. For example, in FIG. 1C, the first oil stop valve 24B (from the separator 70) and the second oil stop valve 24A (for cooling) are off.

The method 400 continues with put compressor on load at 412. For example, in FIG. 1C, the controller 22 may determine to put the air compressor 20 in an on load state based on a need for working air 44 or increased air pressure in the air reserve 70. If the controller 22 determines that the air compressor 20 does not need to be put back into an on load state then the method returns to 412.

The method 400 continues with closing a second path from the air outlet to approximately atmospheric pressure at 414. For example, in FIG. 1B, the controller 22 has closed the isolation valve 12B, and oil can flow in third oil line 39C.

The method 400 continues with opening an air inlet of the air compressor to let air enter the air compressor at 416. For example, in FIG. 1A, the controller 22 has determined to open the adjustable air inlet valve 12A from the closed position to the open position. Steps 414 and 416 may be performed in the opposite order or may be performed simultaneously.

FIG. 5 schematically illustrates an application of the working air. FIG. 5 includes a drilling rig 98, an air compressor system 100, accessory compressed air supply line 504, the outlet of the first receiver 35, working air outlet valve 36, accessory compressed air supply line 504, drilling rig 502, drilling rod 38, drilling hole 40, drilling bit 42, and working air 44, which here is flushing air 44.

The flushing air 44 is compressed air by the compressor system 100 and used to flush the drill hole 40 from the earth crushed by the drill bit 42. The drill hole 40 is the hole formed by the operation of drilling by turning the drill bit 42 and drill rod 38. A drilling rig 502 is configured to turn the drill rod 38 and drill bit 42 and add new drill rods 38 to a drill string.

FIG. 6 schematically illustrates an embodiment of the air compressor system that includes a three way valve 24B, a scavenger line 39E, and a third oil stop valve 24C. Each of the three way valve 24B, scavenger line 39E, and third oil stop valve 24C may be included in the embodiments disclosed herein.

The third oil stop valve 24C may be an oil stop valve 24C configured to control the flow of oil from the receiver 34 to the air compressor 20 in the second oil line 39A. The oil stop valve 24C may be a controlled valve having two positions: a closed position as a default and an open position that the oil stop valve 24C switches to when pressure is applied to the pressure actuator 47. The oil stop valve 24C may have a spring that keeps the oil stop valve 24C in the closed position unless the air pressure actuator 47 pushes on the oil stop valve 24C. The air pressure actuator 47 may be an actuator in communication with the air pressure of the air compressor 20 and the oil stop valve 24C via air line 53. When the air pressure of the air compressor 20 rises past a threshold shutoff oil air pressure the air pressure actuator 47 opens the oil stop valve 24C and when the air pressure of the air compressor 20 falls below a predetermined shutoff oil air pressure the air pressure actuator 46 no longer opens the oil stop valve 24C, so the oil stop valve 24C closes. As discussed above, the second oil line 39B may supply lubricating oil to the air compressor 20. The third oil stop valve 24C may have the advantage that shutting off the lubricating oil to the oil compressor 20 when the oil compressor 20 is not running the oil from the receiver 34 will not flow to the air compressor 20 where it is not needed when the air compressor 20 is not operating.

Fifth oil line 39E may be an oil line 39E suitable for transporting oil from the oil separator 70 to the air inlet 19 of the air compressor 20 at 79. The oil separator 70 may separate oil from the compressed air prior to the compressed air flowing out the air outlet 92 of the oil separator 70, which may be a receiver. In embodiments, there may be an oil stop valve (not illustrated) configured to stop the flow of oil from the oil separator 70 to the air inlet 19 of the air compressor 20. A transceiver (not illustrated) may be configured to control the oil stop valve and may be in communication with the controller 22. The oil stop valve may be configured to be open when air is being pushed into oil separator 70, and closed when air is not being pushed into oil separator 70. The fifth oil line 39E may transport oil from the oil separator 70 to a place other than the air inlet 19 of the air compressor 20 so that the oil reaches the air compressor 20. The air inlet 19 of the air compressor 20 may have a low air pressure so that the oil will flow from the air separator 70 to the air inlet 19 of the air compressor 20.

The third oil stop valve 24C may be a three-way valve with additional sixth oil line 39F that may permit oil to flow from the oil separator 37 to the air compressor 20. In embodiments, the low air pressure at the air inlet 19 of the air compressor 20, draws the oil from the receiver 34 and the oil flows through sixth oil line 39F.

FIG. 7 illustrates an example graph 700 illustrating the operation of an embodiment of the invention when the air compressor is off load. Illustrated in FIG. 7 is the engine speed 720 in revolutions per minute (RPM) of the engine 18 (referring back to FIG. 1), the fuel consumption 722 of the engine 18 in liters per hour (L/Hr), and the intake manifold pressure in inches of mercury (InHg). The intake manifold pressure is, for example, the pressure at approximately 19 (referring back to FIG. 1). The graph 700 illustrates the fuel saving that is realized by example embodiments of the invention.

The graph 700 is divided into three sections 702, 704, and 706. In the first section 702, the RPMs 720 of the engine 18 are in high idle, which here is approximately 1800 RPMs, and the intake manifold pressure 724 is low, which here is approximately 20 InHg. In the second section 704 the RPM's 720 of the engine 18 are in low idle, which here is approximately 1200 RPMs, and the intake manifold pressure 724 is low, which here is approximately 20 InHg. In the third section 706 the RPM's 720 of the engine 18 are in high idle, which here is approximately 1800 RPMs, and the intake manifold pressure 724 is high, which here is approximately 40 InHg. The graph illustrates the fuel consumption when the air compressor 20 is off load so that the adjustable air intake valve 12A is closed for the entire graph 700.

The first section 702 and the second section 704 illustrate the fuel consumption 722 for different states of the oil stop valves 24A and 24B. The highest peaks, which correspond to the highest fuel consumption, are 712, 716 which illustrate when oil stop valve 24B is open and oil stop valve 24A is open. The scavenger oil corresponds to the oil that flows through oil stop valve 24B, and the cooling oil corresponds to the oil that flows through oil stop valve 24A. At peaks 708, oil stop valve 24A is open and oil stop valve 24B is closed. So, the cooling oil is flowing and the scavenger oil is not. At peaks 710, oil stop valve 24A is closed and oil stop valve 24B is open. At peaks 710, the cooling oil is not flowing, but the scavenger oil is flowing.

The lowest levels of fuel consumption are at troughs 714, 718 where oil stop valves 24A and 24B are closed.

The first section 702 and second section 704 illustrate the advantage of fuel savings that is realized by closing the scavenger oil and the cooling oil to the air compressor.

The third section 706 illustrates the fuel consumption of the engine 18 when the air intake pressure is high so that the air in the air compressor 20 may not have been evacuated by one of the methods disclosed herein. The difference in fuel consumption between the third section 706, which is approximately 90 liters/hour, is higher than the fuel consumed with the air evacuated from the air compressor 20 in the first section 702 and the second section 704, which is approximately 40 liters/hour and 30 liters/hour, respectively. The large gain in fuel efficiency between the first section 702 and second section 704, compared with the third section 706 may be due to the evacuation of the air from the air compressor 20.

Embodiments have the advantage that an evacuation pump does not need to be used to lower the air pressure at the outlet valve of the air compressor. Embodiments have the advantage that a large evacuation pump does not need to be used if the air pressure in the reserve is high. For example, the air pressure in the reserve may be 350-500 PSI which would require a large evacuation pump to evacuate the air from the air outlet of the air compressor to the reserve with 350-500 PSI.

The term determine includes looking up values in a table that may have been pre-loaded or pre-calculated as well as other forms of acquiring a calculated quantity that does not involve expressly calculating the quantity, but may involve retrieving the quantity from a storage location that may either be local or remote.

Embodiments may be embodied as kits for upgrading existing air compressor systems. The upgrade kits may include parts for upgrading an existing air compressor system. The parts may include any of the parts described above and embodiments of the methods described above in the forms described below such as a computer readable medium or a ROM memory. Additionally, the kits may include instructions for upgrading existing air compressor systems to embodiments of the invention described above and may include instructions for downloading an embodiment of a method described above from the Internet and/or from a remote or local computer.

Although the explanation above was limited to drilling rigs, it should be understood that the disclosed air compressor system and methods of operation thereof are not limited to drilling rigs and may be used in many other applications.

Although additions have been made to this disclosure, these additions should not be construed to limit the previous disclosure as not including the additions.

The various illustrative logics, logical blocks, modules, and circuits described in connection with the embodiments disclosed herein may be implemented or performed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a programmable logic controller (PLC) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but, in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

Further, the steps and/or actions of a method or algorithm described in connection with the controller 22 disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium may be coupled to the processor, such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. Further, in some aspects, the processor and the storage medium may reside in an ASIC. Additionally, the ASIC may reside in a user terminal. In the alternative, the processor and the storage medium may reside as discrete components in a user terminal. Additionally, in some aspects, the steps and/or actions of a method or algorithm may reside as one or any combination or set of instructions on a machine readable medium and/or computer readable medium.

The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion. The computer readable recording medium may be limited to non-transitory computer readable recording medium.

Although described in connection with preferred embodiments thereof, it will be appreciated by those skilled in the art that additions, deletions, modifications, and substitutions. 

1. An air compressor system, comprising: an air compressor having an air inlet and an air outlet, the air compressor configured to compress air from the air inlet and to deliver a volume of compressed air to the air outlet; an adjustable air inlet valve connected to the air inlet of the air compressor, wherein the adjustable air inlet valve is configured to be adjustable to regulate how much air can flow into the air inlet of the air compressor; a first receiver having an air inlet and an air outlet, the first receiver configured to store compressed air; a main air discharge passage connected to the air outlet of the air compressor and the air inlet of the first receiver; a first non-return valve disposed in the main air discharge passage between the air outlet of the air compressor and the air inlet of the receiver; a second receiver having an air inlet and an air outlet, the second receiver configured to separate oil from compressed air; a secondary discharge passage connected to the air inlet of the second receiver and the main air discharge passage upstream from the first non-return valve; an oil separator disposed in the first receiver; a first oil line disposed to permit oil to flow from the oil separator to the air compressor; a first oil stop valve disposed in the first oil line and configured to have an open position where oil can flow between the oil separator and the air inlet of the air compressor and a closed position where the oil cannot flow between the oil separator and the air inlet of the air compressor; a second oil line disposed to permit oil to flow from the first receiver to the air compressor; a second oil stop valve disposed in the second oil line and configured to have an open position where oil can flow from the first receiver to the air compressor and a closed position where oil cannot flow from the first receiver to the air compressor; an isolation valve disposed in the air flow between the main air discharge passage and the air inlet of the second receiver, wherein the isolation valve is configured to have an open position where air from the main air discharge passage can flow through the secondary discharge passage and a closed position where air from the main air discharge passage cannot flow through the secondary discharge passage; and a controller in communication with the adjustable air inlet valve and the isolation valve, wherein the controller is configured to take the air compressor off load by shutting the adjustable air inlet valve and opening the isolation valve, wherein the first oil stop valve and the second oil stop valve are configured to be open when the air compressor is on load and to be closed when the air compressor is off load.
 2. The air compressor system of claim 1, further comprising: a second non-return valve disposed in the air flow between the secondary discharge passage and the air outlet of the second receiver;
 3. The air compressor system of claim 1, wherein the second non-return valve is configured to maintain the second receiver at approximately atmospheric pressure.
 4. The air compressor system of claim 1, further comprising a third oil line configured to permit oil to flow from the first receiver to the air compressor.
 5. The air compressor system of claim 1, wherein the controller is further configured to first shut the adjustable inlet valve and then after waiting a predetermined time to open the isolation valve.
 6. The air compressor system of claim 1, further comprising an engine configured to drive the air compressor.
 7. The air compressor system of claim 2, wherein the second non-return valve is disposed between the air outlet of the second receiver and atmospheric air.
 8. The air compressor system of claim 1, further comprising a secondary air compressor having an air inlet and an air outlet, wherein the air inlet is disposed to compress air from the air outlet of the compressor to deliver a volume of compressed air to the air inlet of the second receiver, and wherein the controller is further configured to turn on the secondary air compressor after opening the isolation valve and closing the adjustable air inlet valve.
 9. The air compressor system of claim 1, further comprising a pressure sensor in communication with the controller and disposed to measure the pressure of the first receiver, wherein the controller is further configured to determine when to take the air compressor off load based at least partially on the measured air pressure of the first receiver, and wherein the controller is configured to take the air compressor off load by closing the adjustable air inlet valve, opening the isolation valve, and turning the secondary air compressor on.
 10. The air compressor system of claim 1, further comprising an oil line connected to the second receiver and connected to one of: the main discharge passage upstream from the first non-return valve, the main discharge passage downstream from the first non-return valve, and the first receiver.
 11. The air compressor system of claim 1, further comprising a second isolation valve in communication with the controller; a pressure sensor in communication with the controller and disposed to measure the pressure of the first receiver, wherein the controller is further configured to take the air compressor off load by determining a pressure of the first receiver, and if the pressure of the first receiver is below a threshold value then closing the isolation valve and opening the second isolation valve, otherwise opening the isolation valve and closing the second isolation valve; and a secondary air compressor having an air inlet and an air outlet, wherein the air inlet is disposed to compress air from the air outlet of the compressor to deliver a volume of compressed air to the secondary discharge passage, and wherein the controller is further configured to turn on the secondary air compressor after closing the adjustable air inlet valve.
 12. A method of decompressing an air compressor having an air inlet and an air outlet, the method comprising: compressing air from an air inlet to an air outlet, the compressed air flowing through a first path through a first non-return valve to a first receiver; and in response to determining to take the air compressor off-load, closing an air inlet valve of the air compressor to stop air from entering the air compressor, opening a second path from the air outlet of the air compressor to approximately atmospheric pressure to lower the air pressure at the air outlet of the air compressor, stopping a first flow of oil from the first receiver to the air compressor, wherein the first flow of oil is for cooling the compressor, stopping a second flow of oil from a separator for a working air to the air compressor, and flowing oil from the first receiver to the air compressor for lubrication.
 13. The method of claim 12, wherein opening a second path comprises: opening a second path by opening a second non-return valve from the air outlet of the air compressor to a second receiver, wherein the second receiver is at approximately atmospheric pressure.
 14. The method of claim 12, wherein opening a second path includes opening a second path by opening an isolation valve, wherein the isolation valve is connected to the air outlet of the air compressor upstream from the first non-return valve.
 15. The method of claim 12, wherein stopping air from entering the air inlet of the compressor comprises: stopping air from entering the air inlet of the air compressor by closing an air inlet valve of the compressor.
 16. The method of claim 12, further comprising turning on a second air compressor disposed in the second path to suck air out of the air inlet of the air compressor.
 17. The method of claim 12, wherein the second reserve is connected to a non-return valve and the non-return valve is connected to atmospheric pressure.
 18. The method of claim 12, further comprising separating oil from the compressed air in the second receiver and flowing the oil to the first receiver.
 19. A method of decompressing an air compressor having an air inlet and an air outlet, the method comprising: compressing air from an air inlet to an air outlet, the compressed air flowing through a first path through a first non-return valve to a first receiver; and in response to determining to take the air compressor off-load, closing an air inlet valve of the air compressor to stop air from entering the air compressor, and if a receiver pressure is above a threshold, then opening a second path from the air outlet of the air compressor to approximately atmospheric pressure, otherwise opening a third path from the air outlet of the air compressor to the first receiver.
 20. The method of claim 19, further comprising stopping a first flow of oil from the first receiver to the air compressor, wherein the first flow of oil is for cooling the compressor, stopping a second flow of oil from a separator for a working air to the air compressor, and flowing oil from the first receiver to the air compressor for lubrication. 